Left-click brings up view port shading
For some odd reason this has happened to a student of mine several times. When we go to her keymaps we find Context enum menu mapping mapped to left click. She has not did that herself but it comes back even after reinstall etc. I have no idea why but it happens.
Taking the tick off the context enum menu or changing it to something else works (for example the normal E).
Go to
Edit &gt; Preferences &gt; Keymap, search for Context Enum or Left Mouse to find it.

Your keymap might look like this

It should look like this